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chromatin conformation

Stefan Grob, Ueli Grossniklaus
Nuclear organization and higher-order chromosome structure in interphase nuclei are thought to have important effects on fundamental biological processes, including chromosome condensation, replication, and transcription. Until recently, however, nuclear organization could only be analyzed microscopically. The development of chromatin conformation capture (3C)-based techniques now allows a detailed look at chromosomal architecture from the level of individual loci to the entire genome. Here we provide a robust Hi-C protocol, allowing the analysis of nuclear organization in nuclei from different wild-type and mutant plant tissues...
2017: Methods in Molecular Biology
Atsushi Matsuda, Haruhiko Asakawa, Tokuko Haraguchi, Yasushi Hiraoka
The fission yeast Schizosaccharomyces pombe is a useful experimental system for studying the organization of chromosomes within the cell nucleus. S. pombe has a small genome that is organized into three chromosomes. The small size of the genome and the small number of chromosomes are advantageous for cytological and genome-wide studies of chromosomes; however, the small size of the nucleus impedes microscopic observations owing to limits in spatial resolution during imaging. Recent advances in microscopy, such as super-resolution microscopy, have greatly expanded the use of S...
October 21, 2016: Yeast
Soya Shinkai, Tadasu Nozaki, Kazuhiro Maeshima, Yuichi Togashi
The mammalian genome is organized into submegabase-sized chromatin domains (CDs) including topologically associating domains, which have been identified using chromosome conformation capture-based methods. Single-nucleosome imaging in living mammalian cells has revealed subdiffusively dynamic nucleosome movement. It is unclear how single nucleosomes within CDs fluctuate and how the CD structure reflects the nucleosome movement. Here, we present a polymer model wherein CDs are characterized by fractal dimensions and the nucleosome fibers fluctuate in a viscoelastic medium with memory...
October 2016: PLoS Computational Biology
Yi Shi, Xian-Bin Su, Kun-Yan He, Bing-Hao Wu, Bo-Yu Zhang, Ze-Guang Han
Somatic mutations of many cancer genes tend to co-occur (termed co-mutations) in certain patterns during tumor initiation and progression. However, the genetic and epigenetic mechanisms that contribute to the co-mutations of these cancer genes have yet to be explored. Here, we systematically investigated the association between the somatic co-mutations of cancer genes and high-order chromatin conformation. Significantly, somatic point co-mutations in protein-coding genes were closely associated with high-order spatial chromatin folding...
October 20, 2016: Scientific Reports
Hyejung Won, Luis de la Torre-Ubieta, Jason L Stein, Neelroop N Parikshak, Jerry Huang, Carli K Opland, Michael J Gandal, Gavin J Sutton, Farhad Hormozdiari, Daning Lu, Changhoon Lee, Eleazar Eskin, Irina Voineagu, Jason Ernst, Daniel H Geschwind
Three-dimensional physical interactions within chromosomes dynamically regulate gene expression in a tissue-specific manner. However, the 3D organization of chromosomes during human brain development and its role in regulating gene networks dysregulated in neurodevelopmental disorders, such as autism or schizophrenia, are unknown. Here we generate high-resolution 3D maps of chromatin contacts during human corticogenesis, permitting large-scale annotation of previously uncharacterized regulatory relationships relevant to the evolution of human cognition and disease...
October 19, 2016: Nature
Saeed Izadi, Ramu Anandakrishnan, Alexey V Onufriev
Molecular Dynamics (MD) simulations based on the implicit solvent generalized Born (GB) models can provide significant computational advantages over the traditional explicit solvent simulations. However, the standard GB becomes prohibitively expensive for all-atom simulations of large structures; the model scales poorly, ~n^2, with the number of solute atoms. Here we combine our recently developed Optimal Point Charge Approximation (OPCA) with the Hierarchical Charge Partitioning (HCP) approximation to present an ~n log n multi-scale, yet fully atomistic, GB model (GB-HCPO)...
October 17, 2016: Journal of Chemical Theory and Computation
Tsung-Han S Hsieh, Geoffrey Fudenberg, Anton Goloborodko, Oliver J Rando
We present Micro-C XL, an improved method for analysis of chromosome folding at mononucleosome resolution. Using long crosslinkers and isolation of insoluble chromatin, Micro-C XL increases signal-to-noise ratio. Micro-C XL maps of budding and fission yeast genomes capture both short-range chromosome fiber features such as chromosomally interacting domains and higher order features such as centromere clustering. Micro-C XL provides a single assay to interrogate chromosome folding at length scales from the nucleosome to the full genome...
October 10, 2016: Nature Methods
Charles P Fulco, Mathias Munschauer, Rockwell Anyoha, Glen Munson, Sharon R Grossman, Elizabeth M Perez, Michael Kane, Brian Cleary, Eric S Lander, Jesse M Engreitz
Gene expression in mammals is regulated by noncoding elements that can impact physiology and disease, yet the functions and target genes of most noncoding elements remain unknown. We present a high-throughput approach that uses CRISPR interference (CRISPRi) to discover regulatory elements and identify their target genes. We assess >1 megabase (Mb) of sequence in the vicinity of 2 essential transcription factors, MYC and GATA1, and identify 9 distal enhancers that control gene expression and cellular proliferation...
September 29, 2016: Science
Jonathon D Brzezinski, Apexa Modi, Mengdan Liu, Monica J Roth
: Murine Leukemia Virus (MLV) p12, encoded within Gag, binds the viral preintegration complex (PIC) to the mitotic chromatin. This acts to anchor the viral PIC in the nucleus as the nuclear envelope reforms post-mitosis. Mutations within the p12 C-terminus (p12 PM13-15) block early stages in viral replication. Within the p12 PM13 region (p12 60PSPMA65), our studies indicated that chromatin tethering is not detected when the wild type p12 protein (M63) was expressed as a GFP fusion, however, constructs bearing p12-I63 were tethered...
October 5, 2016: Journal of Virology
Martin Franke, Daniel M Ibrahim, Guillaume Andrey, Wibke Schwarzer, Verena Heinrich, Robert Schöpflin, Katerina Kraft, Rieke Kempfer, Ivana Jerković, Wing-Lee Chan, Malte Spielmann, Bernd Timmermann, Lars Wittler, Ingo Kurth, Paola Cambiaso, Orsetta Zuffardi, Gunnar Houge, Lindsay Lambie, Francesco Brancati, Ana Pombo, Martin Vingron, Francois Spitz, Stefan Mundlos
Chromosome conformation capture methods have identified subchromosomal structures of higher-order chromatin interactions called topologically associated domains (TADs) that are separated from each other by boundary regions. By subdividing the genome into discrete regulatory units, TADs restrict the contacts that enhancers establish with their target genes. However, the mechanisms that underlie partitioning of the genome into TADs remain poorly understood. Here we show by chromosome conformation capture (capture Hi-C and 4C-seq methods) that genomic duplications in patient cells and genetically modified mice can result in the formation of new chromatin domains (neo-TADs) and that this process determines their molecular pathology...
October 5, 2016: Nature
Prem Prakash Kushwaha, Krishna Chaitanya Rapalli, Shashank Kumar
DNA replicates in a timely manner with each cell division. Multiple proteins and factors are involved in the initiation of DNA replication including a dynamic interaction between Cdc10-dependent transcript (Cdt1) and Geminin (GMNN). A conformational change between GMNN-Cdt1 heterotrimer and heterohexamer complex is responsible for licensing or inhibition of the DNA replication. This molecular switch ensures a faithful DNA replication during each S phase of cell cycle. GMNN inhibits Cdt1-mediated minichromosome maintenance helicases (MCM) loading onto the chromatin-bound origin recognition complex (ORC) which results in the inhibition of pre-replication complex assembly...
October 1, 2016: Biochimie
Andrew A Kelso, Steven D Goodson, Leah E Watts, LeAnna L Ledford, Sarah M Waldvogel, J Nathaniel Diehl, Shivani B Shah, Amanda F Say, Julie D White, Michael G Sehorn
Homologous recombination (HR) is a template-driven repair pathway that mends DNA double-stranded breaks (DSBs), and thus helps to maintain genome stability. The RAD51 recombinase facilitates DNA joint formation during HR, but to accomplish this task, RAD51 must be loaded onto the single-stranded DNA. DSS1, a candidate gene for split hand/split foot syndrome, provides the ability to recognize RPA-coated ssDNA to the tumor suppressor BRCA2, which is complexed with RAD51. Together BRCA2-DSS1 displace RPA and load RAD51 onto the ssDNA...
September 30, 2016: Nucleic Acids Research
Hui-Yun Liu, Qi Zhao, Tian-Peng Zhang, Yue Wu, Yun-Xia Xiong, Shi-Ke Wang, Yuan-Long Ge, Jin-Hui He, Peng Lv, Tian-Miao Ou, Jia-Heng Tan, Ding Li, Lian-Quan Gu, Jian Ren, Yong Zhao, Zhi-Shu Huang
G-quadruplexes are specialized secondary structures in nucleic acids that possess significant conformational polymorphisms. The precise G-quadruplex conformations in vivo and their relevance to biological functions remain controversial and unclear, especially for telomeric G-quadruplexes. Here, we report a novel single-chain variable fragment (scFv) antibody, D1, with high binding selectivity for parallel G-quadruplexes in vitro and in vivo. Genome-wide chromatin immunoprecipitation using D1 and deep-sequencing revealed the consensus sequence for parallel G-quadruplex formation, which is characterized by G-rich sequence with a short loop size (<3 nt)...
October 20, 2016: Cell Chemical Biology
Michele Di Pierro, Bin Zhang, Erez Lieberman Aiden, Peter G Wolynes, José N Onuchic
In vivo, the human genome folds into a characteristic ensemble of 3D structures. The mechanism driving the folding process remains unknown. We report a theoretical model for chromatin (Minimal Chromatin Model) that explains the folding of interphase chromosomes and generates chromosome conformations consistent with experimental data. The energy landscape of the model was derived by using the maximum entropy principle and relies on two experimentally derived inputs: a classification of loci into chromatin types and a catalog of the positions of chromatin loops...
September 29, 2016: Proceedings of the National Academy of Sciences of the United States of America
Vijay Ramani, Darren A Cusanovich, Ronald J Hause, Wenxiu Ma, Ruolan Qiu, Xinxian Deng, C Anthony Blau, Christine M Disteche, William S Noble, Jay Shendure, Zhijun Duan
With the advent of massively parallel sequencing, considerable work has gone into adapting chromosome conformation capture (3C) techniques to study chromosomal architecture at a genome-wide scale. We recently demonstrated that the inactive murine X chromosome adopts a bipartite structure using a novel 3C protocol, termed in situ DNase Hi-C. Like traditional Hi-C protocols, in situ DNase Hi-C requires that chromatin be chemically cross-linked, digested, end-repaired, and proximity-ligated with a biotinylated bridge adaptor...
November 2016: Nature Protocols
Ill-Min Chung, Sarada Ketharnathan, Seung-Hyun Kim, Muthu Thiruvengadam, Mari Kavitha Rani, Govindasamy Rajakumar
Proximity ligation assays such as circularized chromosome conformation capture and high-throughput chromosome capture assays have shed light on the structural organization of the interphase genome. Functional topologically associating domains (TADs) that constitute the building blocks of genomic organization are disrupted and reconstructed during the cell cycle. Epigenetic memory, as well as the sequence of chromosomes, regulate TAD reconstitution. Sub-TAD domains that are invariant across cell types have been identified, and contacts between these domains, rather than looping, are speculated to drive chromatin folding...
2016: Genes
Wulan Deng, Gerd A Blobel
Chromosome conformation capture (3C) technology and its derivatives are currently the primary methodologies measuring contacts among genomic elements. In fact, the lion share of what is currently known about chromosome folding is based on 3C-related approaches. For example, distal enhancers are commonly in physically proximity with their target genes, forming chromatin loops. Additional layers of chromatin organization have been described using 3C-based techniques, including topological domains (TADs) and sub-TADs...
2017: Methods in Molecular Biology
Benjamin Leblanc, Itys Comet, Frédéric Bantignies, Giacomo Cavalli
4C methods are useful to investigate dependencies between regulatory mechanisms and chromatin structures by revealing the frequency of chromatin contacts between a locus of interest and remote sequences on the chromosome. In this chapter we describe a protocol for the data analysis of microarray-based 4C experiments, presenting updated versions of the methods we used in a previous study of the large-scale chromatin interaction profile of a Polycomb response element in Drosophila. The protocol covers data preparation, normalization, microarray probe selection, and the multi-resolution detection of regions with enriched chromatin contacts...
2016: Methods in Molecular Biology
Mélody Matelot, Daan Noordermeer
3D chromatin organization is essential for many aspects of transcriptional regulation. Circular Chromosome Conformation Capture followed by Illumina sequencing (4C-seq) is among the most powerful techniques to determine 3D chromatin organization. 4C-seq, like other modifications of the original 3C technique, uses the principle of "proximity ligation" to identify and quantify ten thousands of genomic interactions at a kilobase scale in a single experiment for predefined loci in the genome.In this chapter we focus on the experimental steps in the 4C-seq protocol, providing detailed descriptions on the preparation of cells, the construction of the circularized 3C library and the generation of the Illumina high throughput sequencing library...
2016: Methods in Molecular Biology
Hua-Bing Li
Linear chromatin fiber is packed inside the nuclei as a complex three-dimensional structure, and the organization of the chromatin has important roles in the appropriate spatial and temporal regulation of gene expression. To understand how chromatin organizes inside nuclei, and how regulatory proteins physically interact with genes, chromosome conformation capture (3C) technique provides a powerful and sensitive tool to detect both short- and long-range DNA-DNA interaction. Here I describe the 3C technique to detect the DNA-DNA interactions mediated by insulator proteins that are closely related to PcG in Drosophila, which is also broadly applicable to other systems...
2016: Methods in Molecular Biology
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